1. Field of the Invention
The invention relates to a rotor of hollow design in its interior for thermal turbomachines.
2. Discussion of Background
It is known to construct rotors for steam and gas turbines, compressors and turbogenerators from individual rotary bodies having hollow spaces. DE 26 33 829 C2, for example, discloses rotors which are constructed from disk-shaped or hollow-cylindrical forgings, the individual disks or drums (hollow cylinders) in the center part of the rotor preferably having a constant thickness. In this arrangement, the disks or drums are connected to one another by means of low-volume welds.
In order to keep, for example, the operating temperatures of gas turbine rotors approximately constant during full-load operation, these gas turbine rotors must be cooled. For this purpose, it is conventional practice to introduce cooling air through the exhaust-gas-side shaft end into the rotor. There is therefore a central bore in the rotor, which central bore extends from the exhaust-gas-side shaft end up to the last turbine disk. This bore forms the rotor cooling-air duct. The cooling air is extracted from a certain compressor stage and is introduced via a special pipeline into the central bore at the exhaust-gas-side end of the rotor, the transition of pipeline/rotor being sealed off with labyrinth seals. The cooling air flows through the rotor cooling-air duct and then through the hollow space between the two turbine disks before it passes the turbine blades or passes through radial hollow spaces to the rotor surface and mixes with the exhaust-gas flow.
With this known arrangement, although cooling of the rotor is possible once full-load operation is reached, so that small blade clearances and high efficiencies are thereby realizable, positive influencing of the rotor under transient operating conditions, which are especially critical on account of the different thermal behavior of rotor and stator, is not possible.